Backyard Aquaponics
A place to discuss aquaponics

I don't think the direct drive would work... With the 'paint stirrer' even partly submerged in the water would create a large amount of drag and would require a very large wind to start it. A archemides screw would be ideal for a direct drive setup.

I agree that an Archemides screw would work well for low wind speed start ups, but would it disturb the water enough to be of much use?

Plus it has to sit into the water at an angle, thus requiring an articulated joint.

As well, I'm not sure how I would go about making one from available non metallic or reactive materials.

What if the paint stirrer floated on top of the water with just fingers below the surface? Then the resistance is the surface tension and the amount displaced by the fingers.

I bet there`s a flexi-drive shaft made of non metallic materials out there somewhere that could be pressed into service

The main shaft to the windmill could be steel, the part that goes into the water could be just a few thicknesses of pvc tube.
A bearing on the steel would take care of any lateral movement and the weight. Some kind of diy gasket (like a cone or small umbrella) above the bearing would stop water travelling down the mast to the tank.
If the mast is coming through the greenhouse roof it`d be pretty easy to add a cone to redirect the water onto the roof.

What about buying a heavy duty or reasonable quality 12 volt air compressor, eg. the kind for pumping up tyres. Take the motor out of it and attach the drive from the wind mill to it. Run the hose down and run a large air stone on the bottom of the tank, or via a PVC air storage tank, with a small regulator. That way you will still have bubbles when the wind dies.

Or better yet build a large piston style air pump, bit more work but you can get greater air output.

eg: http://www.malibuwater.com/

thanks for the link TC.
I was hoping to do some thing more basic
thinking of an air drill(?) where air is forced down a tube
to the bottom of the tank via a screw,
Like a drill in reverse, so rather than extracting swaff(?) it
pushes air.
Even if its a mix of water and air, it would be helping
to prevent stratification.

I would LOVE to get a Dyno-Aire windmill airpump, but the cost is too prohibitive with everything else we have going on right now. And I have no idea how I would go about making one that would do the same job. But I'm open to suggestions! :-)

What I suggested would work quite well. Use the windmill to drive a cheap (sub $40) air compressor. Run it via a storage tank (2" PVC with two end caps) and have a smaller hole out for the air stone(s).

EDIT:

Here is a good discussion... http://www.fieldlines.com/story/2004/10/23/11533/778

Tim, aren't those air pumps driven by a super fast rpm low torque dc motor?

might have trouble with a higher torque low rpm S rotor.

For the ease of construction i recon give the fish finger maker a go! Just use a junked plastic radiator fan blade.

If the drag affects starting torque as tim says then atlesat you have the rotor and vertical shaft already in place to be hooked up to something else

The air compressors are geared down maybe 20:1. Even then the DC motors that come with them struggle, that is why they die so quick.

The other downside is that it would be fairly noisy, unless you buy a solid unit, keep it well lubricated and built into a solid housing.

Just one idea (if feasible) for somebody interested to try,

Horizontal windmill, with shaft within ball bearing brackets,
but sliding up or down within the bearings.

The bottom part fixed to a big enough floatball to support it.

The ball will have small pallets, (scoops) or something to spray the water as its spinning.

No gears, and will be always at the water level as it changes.

Any takers? cheers, Steve S.

Right angle drives try an old wippersniper head they are 1 to1 and virtually no friction

hmmm, we've got one of those....

i always thought i was like a speedo cable setup i them?

what a bout a worm drive ??

they are used in portable shearing plants there is even a few different types, one is like what steve is suggesting basicaly a large coil

and there is another type that is less flexable thats made from plastic though this one is used in standard shearing heads and has much less felxability

both are quite strong if i rememebr rightly shearing heads spin at 2500 rpm

After some research i figured you shouldn`t need to shift the transmission thru 90 degrees..you just need a different stirrer design.

These are very interesting, and if the specs can be believed, more than enough for any size fishtank/pond.

http://www.oloid.ch/frame.php3?lang=en& ... oid_typ200

No clue what they retail at..but i bet it`s pricey.

They only draw 30w when aerating or 60w when agitating/circulating and needs 55rpm- 125rpm which should be doable with a reasonable windmill.
They do a 15v dc solar powered version too.

Fancy homebrewing one?.. the hardest part will be making the Oloid itself.

A quick peek at the spec pdf and patent #4,784,338 gives a good idea of the dimensions and how it goes together.